Fluids & Electrolytes, and Metabolism Nestor T. Hilvano, M.D., M.P.H. (Illustrations Copyright by Frederic H. Martini, Pearson Publication Inc., and The McGraw-Hill Companies Inc.)

Learning Objectives 1. Compare the composition of the extracellular and intracellular fluids. 2. State the terms for an excess or deficiency of water and electrolytes, and describe their consequences. 3. Define metabolism, anabolism, and catabolism. 4. Describe the processes of carbohydrate, lipid, and protein metabolism.

Fluids and Electrolytes Water- mostly found in ICF (intracellular fluid), medium for diffusion of substances (nutrients, wastes, and gases) Diffusion of substances- from high to low water concentration gradient (passive transport) Solutes (ions, molecules, suspended particles)- can move from low to high concentration gradient (active transport) Osmosis is a diffusion of ___. a. gases (CO 2 & O 2 ) b. water c. salt (NaCl 2 ) d. organic molecule

Fluids and Electrolytes Total body water for 70 kg = 40L (60% of total body wt.) Fluid compartments: a) ICF (intracellular fluid) – 2/3 of total body water; contains high potassium (K +, major cations ), magnesium (Mg + ), phosphate (PO 4 3- ) ions, and proteins (major anions). ECF (extracellular fluid) – 1/3 of total body water; contains high sodium (Na +, major cations ), chloride (Cl - ), and bicarbonate (HCO 3 - ) ions; ECF includes interstitial fluid, blood plasma, and other (lymph, CSF, synovial fluid, serous) fluids. Exercise: Cations are ___ charged atoms.; Anions are ___ charged atoms. a. neutral b. negative c. positive

Disorders of Water Balance Dehydration (water depletion) total body water decrease, osmolarity increase lack of drinking water, diabetes, profuse sweating, diuretics, repeated vomiting, diarrhea most serious effects = circulatory shock, neurological dysfunction, infant mortality

Fluid Excess Volume excess –both Na + and water are retained, ECF isotonic Overhydration (hypotonic hydration) –more water than Na + retained (hyponatremia), ECF hypotonic (water intoxication) –Most serious effects = pulmonary and cerebral edema

Electrolytes Function: –chemically reactive in metabolism –determine cell membrane potentials –affect osmolarity of body fluids –affect body’s water content and distribution Major cations - Na +, K +, Ca 2+, H + What is the dominant cation in the ECF?___. In the ICF? ___. a. K+ b. Na+ c. H+ d. Cl- Major anions - Cl -, HCO 3 -, PO 4 3-, and proteins What is the dominant anions in the ICF? ___. a. Cl- b. HCO 3 - c. proteins d. PO 4 3-

Sodium Functions - Membrane potentials; Na + - K + pump; sodium salts provide 90% ECF osmotic concentration; NaHCO 3 has major role in buffering pH of the ECF Normal concentration mEq/L in ECF; 10 or less mEq/L in ICF Hypernatremia –plasma sodium > 145 mEq/L Hyponatremia –plasma sodium < 130 mEq/L

Potassium Functions - Determines intracellular osmolarity; Membrane potentials; Na + -K + pump Normal concentrations mEq/L in ICF; 3.5 – 5.5 mEq/L in ECF Most dangerous imbalances of electrolytes Hyperkalemia (>5.5 mEq/L) - makes nerve and muscle cells abnormally excitable Hypokalemia (<3.5 mEq/L) - from sweating, chronic vomiting or diarrhea –nerve and muscle cells less excitable

Metabolism Metabolism – all chemical reactions in an organism C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + energy (ATP) ___ - synthesis of new organic molecules (uses energy; perform maintenance and repair; support growth; produce secretions; and store nutrient reserve). ___ - breakdown of organic substrate; process releases energy. a. catabolism b. anabolism

Glucose Catabolism (review) Transfer energy to ATP I. Aerobic (cellular) respiration- major pathways: a. Glycolysis- cytoplasm, net of 2ATP, 2pyruvate, 2NADH a. TCA (Krebs)- mitochondria, 2 acetylCoA, produced 8NADH, 2FADH2, 2ATP,4CO2 a. Oxidative phosphorylation- mitochondrial membrane, ETC and chemiosmosis (creates H+ gradient, ATP synthase), 34 ATP II. Fermentation- anaerobic respiration, end product is lactic acid

Carbohydrate Metabolism ___- synthesis of glucose from non- carbohydrate sources ___- breakdown of glucose into pyruvates ___- formation of glycogen from glucose ___- breakdown of glycogen Liver and skeletal muscle store glycogen. a. glycogenesis b. glycogenolysis c. gluconeogenesis d. glycolysis

Lipid Metabolism Triglycerides are stored in adipocytes, most abundant lipid in blood. ___ - synthesizing fat from other sources –amino acids and sugars used to make fatty acids and glycerol ___ - breaking down fat for fuel a. lipolysis b. lipogenesis fatty acids are broken down to produce acetyl- CoA (beta oxidation), enters krebs, yield energy (144 ATP)

Protein Metabolism ___ What are the building blocks of proteins? a. fatty acids b. amino acids c. nucleotides d. lactic acids Transaminatio n- attaches amino group to amino acid + keto acid; used in protein synthesis, keto acid into krebs Deamination - removes amino group and hydrogen atom to produce ammonium ion (NH4+), which converts into urea (kidneys) * Urea cycle- liver converts ammonia and CO2 to urea, that is excreted in urine

Homework 1. Define terms: dehydration, water intoxication (overhydration), metabolism, catabolism, anabolism, transamination, deamination, glycogenesis, gluconeogenesis, glycolysis, aerobic respiration, anaerobic respiration (fermentation), lipolysis, lipogenesis, cations, anions, osmosis 2. Compare and contrast the extracellular and intracellular fluid compartments as to components or contents (water, cations, and anions).